The victims included a 2-year-old son, Avenir, and a 3-year-old daughter, Emmanuella. A 6-month-old boy, Marc, was found unharmed at the duplex.

Bukhantsov is being held at the Sacramento County Jail, ineligible for bail on three murder charges.

"We don’t know for sure what was the catalyst to lead to this -- obviously, (a) very serious incident -- but everything that we have learned throughout the course of the investigation so far suggests that (Grigoriy Bukhantsov) just didn’t have a good relationship with family members," said Sgt. Jason Ramos, of the Sacramento County Sheriff's Department. "And there have been some suggestions that something bad was brewing for some time. But I don’t think anybody could have foreseen an act of this nature."

Rocklin police caught up with Bukhantsov about 2 a.m. at a Denny's restaurant. He was tracked through a minivan he drove from the home on De Soto Way -- where the killings took place.

The teen was asleep in a booth with a plate of chicken-fried steak with gravy when police approached him. After he was taken in for several hours of questioning, the Sheriff's Department made the arrest.

"We had developed information through the course of the night that had led us to be looking at him -- and information that came from family members," Ramos said.

Bukhantsov didn't have a permanent residence.

"There was information fairly early in the investigation that caused our interest to be directed toward this suspect, but we didn’t want to have tunnel vision," Ramos said. "We never want to limit ourselves to what possibilities may be present, as far as more than one suspect."

Ramos described the manner of the attack as a "sharp force trauma" such as a "stab, slashing, slicing," but declined to say what kind of weapon was used or go into further detail pending a coroner's inquiry. He said there was no forced entry into the home.

It was Bethany Slavic Missionary Church Pastor Stephan Skots who spoke of Denis and Alina on Wednesday morning.

Alina moved to the Sacramento-area from Belarus with her family in 2007, where she soon met Denis, who is originally from the Ukraine.

The pair were married at the church just a few months after announcing their engagement in 2008.

Videos posted online showed the couple posing for wedding pictures in San Francisco and Denis singing a love song in Russian to Alina.

Skots added that Denis is a youth leader and works on the church sound system. Alina taught Sunday school.

"She always helped. She was a young mother with three children. But she was very open to people," Skots told KCRA 3.

Alina, who recently graduated from Sacramento State, was described by friends as a loving mother.

On Wednesday, people were seen leaving balloons, stuffed animals and flowers at the family's home, and the church was planning a funeral service for the victims.

"That family was so loving. They were always holding hands at church. They were always so much in love. She always had a smile on her face," family friend Svetlana Murza said.

Denis Bukhantsov is pictured with his children and wife, Alina. His wife and two of his kids were killed Tuesday. His brother, 19-year-old Grigoriy Bukhantsov, was arrested Wednesday morning on suspicion of the killings.